Applications are divided into two categories: forward use and reverse use of formulas. Among them, the appropriate questions are as follows:

1。 In the multiplication of the following polynomials, XXXXXX can be calculated with or without square difference or complete square formula.

2。 The following calculation is correct: XXXXXXXXXXX.

3。 The result of (xa-xb)2 is XXXXXXXXXXXXXX.

4。 If the result of (xa-yb)2 is XXXXXXXXX, then x= y= investigate the undetermined coefficient method. Or the result does not contain any items, first open the brackets, and then merge similar items. This term does not exist, because the coefficient is 0, so the coefficient is 0, which needs to be solved by letters.

5。 For general calculation problems, you need to know how to set formulas. You need to know which items in the formula are a and b, and there are tricks to recite the formula:

The application of square difference formula is to accurately find out the same term and inverse term in two formulas, and the result is equal to the square of the same term minus the square of the inverse term, and the result is generally only two terms (regardless of the case that a polynomial has three terms). The complete square formula is to find the first term and the last term, and the result is equal to the product of the square of the prime number plus plus plus or minus twice the square of the last term. Students must be reminded that when the coefficients of the first and last items are not 1, they should be used. Finally, I need to remind students that if you have time, you can multiply polynomials by polynomials, because both formulas are essentially derived from polynomials multiplied by polynomials, while polynomials multiplied by polynomials are essentially monomials multiplied by monomials, and monomials multiplied by monomials are closely combined with power operations, so the logical structure of mathematics is closely linked and the foundation is very important.

6。 If there are some quantities of xy, x2y2, x2-y2, x2+y2, x+y and x-y in the topic, first square x+y and x-y, and then find out the remaining quantities by combining conditions. If there is a value of x2-y2, find x+y and x-y respectively, and it will be complete. X2+y2=(x-y)2+2xy, and then add or subtract the two formulas to get two formulas. This is actually the content of symmetry formula in mathematics competition. Of course, we should teach students in accordance with their aptitude.

7。 (xx+xx)(xx+xx)-(xx+xx)(xx+xx) Note that the following results should be enclosed in brackets.

Pay attention to questions like 20102-2009 * 2011!

8。 Comprehensive application of two formulas: (2x+y-3k)(2x-y+3k)= 1